Recently, there is a need for small and high-capacity batteries. For actualizing a high-capacity battery, a multilayer structure is adopted for a battery. FIG. 2 illustrates an example of a multilayer structure of a conventional battery.
FIG. 2(A) illustrates a conventional cylinder-type battery structure in which electrode plates are arranged in a roll structure. In the battery in FIG. 2(A), a positive electrode plate and a negative electrode plate are arranged to be mutually faced to each other and a battery case is sealed after the positive electrode plate and the negative electrode plate with a separator interposed therebetween are wound and stored into the battery case.
FIGS. 2(B) and 2(C) illustrate examples of a battery structure of a conventional rectangular type. In the battery in FIG. 2(B), a battery case is sealed after a positive electrode plate and a negative electrode plate which are mutually faced with a separator interposed therebetween are bent into a rectangular shape or wound and pressed to be flattened and stored into the battery case. In the battery in FIG. 2(C), positive electrode plates and negative electrode plates are alternately inserted to valley grooves of a zigzag-folded separator continuous body and flattened by being pressed in a zigzag direction (see Patent Document 1).
FIG. 2(D) illustrates a structure of a multilayer ceramic capacitor not being a structure of a battery. The multilayer ceramic capacitor illustrated in FIG. 2(D) has a structure that dielectric ceramic and an internal electrode are alternately layered in a comb-shaped manner.
In addition to alkaline storage batteries such as nickel-hydrogen secondary batteries, the battery structures in FIGS. 2(A) to 2(C) have been applied to lithium ion secondary batteries as well.
Further, recently, there have been known solid-state secondary cells structured with solid thin films. FIG. 3(A) is a perspective view illustrating a structure of a solid-state secondary cell and FIG. 3(B) is a sectional view illustrating a section of the solid-state secondary battery. The secondary cell 1 in FIGS. 3(A) and 3(B) includes a solid charging layer 2 between a first electrode layer 3 and a second electrode layer 4 and is expected to actualize a downsized secondary battery.